Firearms and methods for operating the same

ABSTRACT

Firearms and methods of operating the same are disclosed. An example firearm includes a barrel; a bolt head which is movable along a motion path; and a locking block penetrating the bolt head and being movable in a direction substantially transverse to the motion path between a locked position and an unlocked position. The locking block locks the bolt head against movement along the motion path when the locking block is in the locked position. The firearm also includes a bolt head carrier which is movable independently of the bolt head over a lost motion path and an initial path, and which is movable with the bolt head over an end path. The bolt head carrier includes at least one surface positioned to force the locking block from the locked position to the unlocked position as the bolt head carrier travels the initial path. When moving rearward, the bolt head carrier travels the lost motion path before traveling the initial path. The locking block remains in the locked position as the bolt head carrier travels the lost motion path.

RELATED APPLICATION

This patent arises from a U.S. patent application which is (a) a continuation of International Patent Application Ser. No. PCT/EP2003/009491, filed Aug. 27, 2003, (b) a continuation of International Patent Application Ser. No. PCT/EP2003/009483, filed Aug. 27, 2003, and (c) a continuation-in-part of U.S. patent application Ser. No. 10/956,562, filed on Oct. 1, 2004. U.S. patent application Ser. No. 10/956,562 is a continuation of International Patent Application Ser. No. PCT/EP03/09490, which was filed on Aug. 27, 2003. International Patent Application Serial No. PCT/EP2003/009491, International Patent Application Ser. No. PCT/EP2003/009483, International Patent Application Ser. No. PCT/EP03/09490, and U.S. patent application Ser. No. 10/956,562 are all hereby incorporated herein by reference in the entirety.

FIELD OF THE DISCLOSURE

This disclosure relates generally to firearms, and more particularly, to firearms and methods of operating the same.

BACKGROUND

Throughout this patent, position designations such as “above,” “below,” “top” “forward,” “rear,” etc. are referenced to a firearm held in a normal firing position (i.e., pointed away from the shooter in a generally horizontal direction).

Soon after the emergence of the repeating firearms with cylinder breech mechanisms, attempts were made to simplify the loading motion. To load by hand, the marksman had to make a transverse motion, a back motion, a forward motion and again a transverse motion. Consequently, a kind of worm gear was developed, which converts a simple back and forward motion into the above specified complicated movement. Due to the complicated mechanics, these so-called straight pull action systems either did not prove themselves or were too expensive. In the case of these known straight pull action systems, a breech block is assigned to the actual breech or bolt head, which could be viewed as a bolt head carrier.

There are also other systems for simplifying the loading motion. Such a system was realized prior to the above named straight pull action system. In that earlier system, the breech can be moved in a straight line forward until reaching the cartridge base in the cartridge chamber. When the breech reaches this position, a cross slide or locking block is moved into recesses in the breech and into the case of the weapon to thereby lock the breech. A bottom lever is rotated downward in an arc-shaped motion in an initial run to release the locking block. The unlocked breech is then pulled back in an end run. The breech is not closed and locked until the bottom lever is rotated upward. A box magazine has also been known for use with this system since 1895.

Similar systems are not activated by a bottom lever, but rather by a slide which is joined to the fore end and can be moved in a straight line. However, in these systems, the locking block executes a rotating motion.

All of the above described systems are quite complicated and correspondingly expensive and sensitive.

In the case of locking blocks with bottom levers and fore end loaders, particularly in the case of those that use heavy cartridges, high surface pressures occur. These pressures can only be counteracted by awkwardly shaped constructions or extremely high precision.

Particularly in the case of weapons for emergency use, ruggedness, small dimensions, and reliability should be combined with a low price. Such weapons are typically only used in rare emergencies, but then they must function safely under difficult circumstances.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view through the rear part of the barrel piece and the breech of an example shot gun shown with a closed and locked breech.

FIG. 2 is a cross-sectional view of the example weapon of FIG. 1, but showing the weapon with an unlocked breech immediately after the firing of a shot.

FIG. 3.1 is a longitudinal cross-sectional view through the bolt head carrier of FIGS. 1 and 2, but shown in a slightly larger scale than that used in FIGS. 1 and 2.

FIG. 3.2 is a top perspective view of the example bolt head carrier shown in FIG. 3.1.

FIG. 4 is a cross-sectional view through the rear part (end section) of the barrel piece of FIG. 1, shown along the center axis of a locking recess.

FIG. 5.1 is a rear view of the example locking block.

FIG. 5.2 is a side view of the locking block of FIG. 5.1.

FIG. 6 is a top perspective view of the breech shown approximately in the state shown in FIG. 1.

FIG. 7 is a greatly enlarged view of an example extractor claw.

FIG. 8 is a side view of the stripping block.

FIG. 9 is a cross-sectional view of the stripping block, taken along line IX-IX of FIG. 8.

DETAILED DESCRIPTION

The example weapon shown in FIGS. 1 and 2 is a semi-automatic shot gun that can be provided with a case magazine. The shot gun of FIG. 1 has a barrel piece (1) with a center or bore axis (37). A cartridge chamber (3) is located in the rear part of this barrel piece (1). An end section (4) of the barrel piece (1) defines the cartridge chamber (3).

The end section (4) has an almost U-shaped cross-section. As shown in FIG. 4, the U-shaped cross-section of the end section (4) is open on the bottom, has a concentric, upper locking recess (5), and two locking notches (6) on the bottom. The locking notches (6) are located in the free ends of the two legs of the U-shaped cross-section. A groove (10) is provided at approximately half the height of each leg of the U-shaped cross-section. Each groove (10) runs parallel to the bore axis (37). A cartridge extractor (61) such as that shown in FIG. 7, can run in each of these grooves (10).

When the weapon is cocked and ready to fire as shown in FIG. 1, the cartridge chamber 3) is locked toward the back by a bolt head (11). The bolt head (11) is penetrated by a front, vertical, transverse drill hole that receives a locking block (25). As shown in FIG. 5.1, the locking block (25) has an upside-down T-shaped cross-section which is oriented perpendicularly relative to the bore axis (37). The locking block (25) has a conical locking appendage (7) on the free (upper) end of its center shaft. As also shown in FIG. 5.1, the locking block (25) includes a locking finger (8) on each of the two ends of the (lower) transverse shaft. In the locked position, the locking appendage (7) engages with the locking recess (5) and the locking fingers (8) simultaneously engage with their corresponding locking notches (6).

In the example shown in the figures, all of the engagement surfaces are sloped with respect to a vertical line in order to facilitate effortless engagement and detachment of the locking block (25) in the end section (4) of the barrel piece (1). However, in the illustrated example, the sloped angles of the surfaces are so low that the engagement is self-locking, (i.e., the engagement cannot be released by applying a force on the bolt head (11) along the bore axis (37) towards the back of the weapon).

As a result of the engagement of the locking block (25) and the rear section (4) of the barrel piece (1), the barrel piece (1) and the bolt head (11) are directly connected with each other during a shot. Therefore, the barrel piece (1) and the bolt head (11) transfer high initial forces directly to each other. No other element is affected by this transfer of force. The back end of the barrel piece (1) can, therefore, be embedded into a plastic housing (2) because the largest occurring forces are not discharged into the housing (2).

In the illustrated example, the bolt head (11) sits on a bolt head carrier (13), which is shown in detail in FIGS. 3.1 and 3.2. The bolt head carrier (13) can be moved a certain distance longitudinally relative to the bolt head (11). The bolt head carrier (13) has a longitudinal recess (54), a transverse recess (53) in the area below the locking block (25), and level surface (59) behind this recess (53).

The transverse recess (53) is bordered on each side of the longitudinal recess (54) by a nose (55) (see FIG. 3.2). Each nose (55) flanges upward and backward as shown in FIG. 3.1. Each flange terminates at a height above the level surface (59).

The locking block (25) is constructed such that, in its upper locking position, the lower surface of its transverse shaft is rounded off almost flush with the lower surface of the bolt head (11) (FIG. 1). In this position, the bolt head carrier (13) can move forward and backward under the locking block (25) and the bolt head (11), and the locking block (25) can glide on the level surfaces (59) of the bolt head carrier (13).

However, if the bolt head carrier (13) moves backwards from the resting position shown in FIG. 1, then both noses (55) engage the transverse shaft of the locking block (25) with their rear edges. As a result, the noses (55) pull the locking block (25) down into the transverse recess (53) into the position shown in FIG. 2. In this position, the lock block (25) disengages from the end section (4) of the barrel piece (1). As a result of this disengagement, the bolt head (11) is free to move backward relative to the barrel piece (1).

During further backward movement, the unlocked bolt head (11) runs in a guide (not shown) in the housing (2). During this rearward movement, the locking block (25) is held such that it cannot move upward.

When closing, the bolt head (11) hits the rear end of the cartridge chamber (3). The bolt head carrier (13) is then pulled or pushed further forward by a closing spring (9) (shown schematically in FIGS. 1 and 2 as the direction of force (9)). In this process, one taper (57) forming the back wall of the transverse recess (53) cams the locking block (25) in the upward direction until the level surface (59) reaches under the locking block (25) and the position of FIG. 1 is reached once again.

A pivotable stripping block (27) is located in the bolt head (11) behind the locking block (25). The stripping block (27) is held in its position of use by a pin (28) (see FIGS. 1, 2, 6, 8, and 9). The stripping block (27) is located in a rear, vertical transverse bore (23) in the bolt head (11). The pin (28) can be disengaged via the bore hole (24) in the bolt head (11) as shown in FIG. 6.

The locking block (25) and the stripping block (27) are penetrated by a striker or firing pin (19). Each of the locking block (25) and the stripping block (27) has a bore (31), (34) to permit this penetration.

The lower end of the stripping block (27) is constructed as a hammer foot (51). The hammer foot (51) runs in a groove (54) defined in the bolt head carrier (13) (see FIG. 3.2). The groove (54) is open on the top and has an upside-down T-shaped cross-section. In the operational state, (i.e., in the position of use), the hammer foot (51) reaches below the flanks of the groove (54) and the stripping block (27) is held by its pin (28). In this operational state, a projection (35) of the striker/firing pin (19) hits a protrusion (36) (see FIG. 9) located behind it in the bore hole (34) of the stripping block (27). This engagement of the firing pin (19) and the stripping block (27) prevents the striker/firing pin (19) from falling backwards out of the bolt head (11). If the stripping block (27) is rotated by approx. an eighth of a turn (e.g., after removing the pin (28)), then the striker/firing pin (19) can be removed toward the back. Since, in this state, the hammer foot (51) still reaches under the upper flanks of the groove (49), the bolt head (11) and the bolt head carrier (13) still remain assembled, while the striker/firing pin (19) can be replaced with a new one. Only a full quarter turn of the stripping block (27) (which, of course, is only possible after removing the striker/firing pin (19)) releases the hammer foot (51) from the groove (54) and permits the bolt head (11) to be lifted from the bolt head carrier (13).

As shown in FIG. 5.1, the bore (31) in the locking block (25) (which is penetrated by the striker/firing pin (19)) is structured as an elongated hole to permit the locking block (25) to move between the positions of FIGS. 1 and 2 (locked and unlocked) despite the presence of the striker/firing pin (19).

The striker/firing pin (19) has an enlarged section (29) behind the elongated hole (31). As shown in the example of FIG. 5.1, a recess (33) which is sloped complementary to the enlargement (29) is formed in the bottom of the backside of the elongated hole (31). The recess (33) and the enlargement (29) are formed such that the striker/firing pin (19) can only penetrate the elongated hole (29) when the locking block (25) is located in its uppermost position (i.e., the locking position shown in FIG. 1). In this position, the striker (19) can be inserted so far into the elongated hole (31) that its tip can stick out of the front surface of the bolt head (11) for firing a cartridge.

If the locking block (25) is lowered, due to its special form the recess (33) presses the enlargement (29) of the firing pin (19) backward such that the tip of the firing pin (19) cannot reach a cartridge. This ensures that a cartridge can only be fired if the bolt head (11) is properly locked.

The enlargement (29) and the projection (35) cooperate to hold the firing pin (19) loosely between two positions, namely, a forward position and a rearward position. The sloped recess (33) of the locking block (25) forces a withdrawal of the firing pin (19) during unlocking. A striker spring is, thus, generally superfluous and, therefore, does not need to be provided.

A handle such as, for example, a movable front shaft, may be attached to the bolt head carrier (13). A detachable latch may secure this handle in the foremost position. In this case, a closing spring (9) is not required, but rather the handle and, thus, the bolt head carrier (13) are moved back and forth to load the weapon.

When the handle (65) is pulled back, the bolt head carrier (13) is pulled along to the rear. As a result of this rearward movement, the bolt head carrier (13) pulls the locking block (25) down via the noses (55) thereby freeing the bolt head (11) for rearward travel. Therefore, the bolt head carrier (13) pulls the bolt head (11) along in its backwards movement. In the process, the rear end of the bolt head carrier (13) cocks the hammer of a known striking mechanism (not shown), and performs a loading motion. In the opposite, forward motion, the locking block (25) is pressed back up again and supported from below by the upper surface (59) of the bolt head carrier (13), as described above. This operation is not affected by minor positioning differences such as whether the bolt head carrier (13) is located one millimeter further to the front or not or by side-by-side tolerances.

One advantage of the illustrated breech (11, 13) lies in the fact that, in its unlocked state (FIG. 11), the front of the bolt head carrier (13) protrudes to the front of the bolt head (11). This configuration permits a cartridge to be transferred without getting its base caught on a cartridge extractor or on a projection of the front area of the bolt head (11). Additionally, the bolt head (11) is not subjected to stress and will not have a tendency to lock “in transit”.

As can be seen in FIG. 6, the bolt head (11) of the illustrated example is unusual in that it has two opposite lying cartridge extractors (61). A larger version of an example cartridge extractor (61) is shown in FIG. 7. As can be seen in FIG. 7, the example cartridge extractor (61) has a hook-like formation with a hook surface (63) turned toward the rear that is designed to sit on the edge of a shot cartridge from the front. This edge is curved outward and forward so that the hook surface (63) sits on a curved formation. Depending on whether the cartridge extractor is arranged on the left or the right, the cartridge shell is ejected to the left or the right. There is no eccentric or lateral force acting on the cartridge shell during ejection, which force could occur if an individual cartridge extractor was employed. This guarantees the proper ejection of very long cartridge shells. Only near the end of the recoil path of the breech is an eccentric force exerted on the cartridge shell. This eccentric force causes release of the cartridge shell, first from one and then from the other cartridge extractor (61). Therefore, only the ejector needs to be converted to convert from right to left ejection (or vice versa). Both cartridge extractors (61) remain where they are.

An example cartridge ejection arrangement is described in more detail in U.S. Patent application Ser. No. ______ (Attorney Docket No. 20020/10056), which is incorporated in its entirety herein by reference.

From the foregoing, persons of ordinary skill in the art will appreciate that repeating firearms employing a straight pull action have been disclosed. These weapons are suitable for emergency use, as well as for use in the military, by the police force, etc.

Such persons will further appreciate that repeating firearms with a bolt head (11) that can be moved in the longitudinal direction of fire have been disclosed. These firearms have a locking block (25) that can be moved transversely to the direction of fire. For the purpose of locking the breech, the locking block (25) can be inserted in recesses in the breech. Further, the illustrated examples may include a handle (65) for moving the bolt head (11) forward or backward as well as for inserting and releasing the locking block (25).

In an illustrated example, a repeating rifle is provided with a bolt head carrier (13) that can be moved parallel to the bolt head (11) via an initial and final run. The bolt head carrier (13) carries the bolt head (11) with it on the final run. In some disclosed examples, the bolt head carrier (13) has at least one beveled surface (55, 57), which engages in an opposite surface on a locking block (25) carried by the bolt head (11) such that the locking block (25) is released from a locking position or inserted into a locking position when the initial run is made or reversed.

Using a longitudinal slide motion of a straight pull action breech in order to activate a locking block is known from the bottom lever loader system described above. This approach allows the bolt head to be kept very short, which permits the total length of the rifle to be reduced. Since the longitudinally movable bolt head carrier (13) does not need to rest on the locking block (25) in the longitudinal direction, the length of the path of motion of the bolt head carrier (13) does not have to be precisely defined, but rather only has to be long enough to accomplished proper functioning.

It is also practical that the bolt head carrier (13) be permitted to move through a lost motion run prior to the initial run. The breech remains locked during this lost motion run. This lost motion run not only compensates for structural inaccuracies, but also makes it possible for the marksman to gather momentum to facilitate manual operation of the cartridge ejection and loading mechanism. In other words, the locking block (25) will not be unlocked by the bolt head carrier (13) until the bolt head carrier (13) has picked up speed. A breech block (11) is picked up along the process, perhaps without the marksman even noticing anything about the disturbance.

In preferred implementations described above, the case of the weapon is formed by the rear end of the barrel (1) or by a barrel retainer case as well as by a plastic case. Furthermore, the recesses are constructed in the case of the weapon on the rear end of the barrel (1) or in the barrel retainer case. During firing of these preferred weapons, the main recoil forces are immediately conducted from the barrel (1) into the bolt head (11) via the locking block (25). The weapon housing/case, which may be made of plastic, absorbs only parasitic forces. If desired, the housing/case may be provided with flexible parts. The housing protects all the parts from fouling.

Due to the large, structural degree of freedom, the weapons disclosed herein can have practically any kind of appearance. The handle for the bolt head carrier (13) can be the butt, the front shaft, a bottom lever, or simply a handle which protrudes laterally out of the (plastic) weapon housing/case, from the rear or from the front.

Further, in the disclosed firearms, the firing pin (19) is mounted directly on the bolt head (11). More specifically, in the disclosed examples, the firing pin (19) passes through the bolt head (11). However, without further modification, locating the firing pin (19) within the bolt head (11) could permit the cartridge to be fired whenever the bolt head (11) engages the cartridge, irrespective of whether the breech is locked or unlocked.

Therefore, to prevent the firing pin (19) from striking the cartridge when the breech is unlocked, the firing pin (19) penetrates the locking block (25) in the bolt head (11). When the breech is locked (i.e., the locking block (25) is in a locked position), the firing pin (19) may freely pass through the locking block (25). However, when the locking block (25), and, thus, the breech, is in an unlocked state, the firing pin (19) is held in a withdrawn, inoperative position where is cannot reach the base of a cartridge in the cartridge chamber. Consequently the locking block (25) acts, so to speak, as a safety, because the locking block (25) ensures that the trigger can only fire a cartridge when the bolt head (11) is locked.

In the illustrated examples, the locking block (25) has a beveled edge (33) which forces the firing pin (19) back into the inoperative position when the locking block (25) transitions from the locked to the unlocked position. If, for example, as a result of a cartridge defect, the firing pin (19) becomes caught in the blasting cap during the shot, then it is forcibly withdrawn from the blasting cap and brought into the inoperative position by the bevel (33) of the locking block (25) when the locking block (25) moves from the locked position to the unlocked position.

In the illustrated examples, to move in and/or out of the locked position, the locking block (25) moves transversely to the axis (37) of the bore in the bolt head (11). Moreover, the locking block (25) passes through the bolt head (11) and, in the locked position, engages in one or more recesses (5, 6) in a component (4) that is constructed in one piece with the barrel (1) or a component that is rigidly fastened to the barrel (1). Preferably, the engagement between the locking block (25), and the recesses (5, 6) occurs at three places distributed somewhat uniformly over the periphery of the locking block (25). With shotguns, a generous over-dimensioning of the recesses (5, 6) and locking bolt (25) is possible due to the size of the cartridge. The locking bolt (25) is preferably slightly beveled in the sections (7, 8) which engage the recesses (5, 6), so that a gentle locking (above all, for large case tolerances) and unlocking of the locking bolt (25) is always possible.

The bolt head carrier (13) may be structured to be moved on the side of the bolt head (11) opposite the recess (5). In some examples, the locking block (25) has front and rear foot strips (8) and the bolt head carrier (13) has front (55) and rear (57) carrying strips positioned so that the front carrier strips (57) of the rearward moving bolt head carrier (13) run into the front foot strips (8) of the locking block (25) in order to extract the locking block from the recesses (5, 6). During the closing motion, the rear carrier strips (57) of the bolt head carrier (13) run into the rear foot strips (8) of the locking block (25) and forces the locking block (25) into the recess (5, 6). Preferably, at least one each of the front or rear foot strips (8) and the carrier strips (55, 57) is beveled.

When the bolt head (11) is locked, then the bolt head carrier (13) can be moved freely forward up to the position that it occupies after locking has been completed. If the bolt head carrier (13) moves from this position to the rear, then after a more or less large lost motion run, the bolt head carrier (13) pulls the locking block (25) out of the recesses (5, 6) and then carries the bolt head (11) along to the rear. In this process, the length of the lost motion path that is formed between the foot strips (8) of the locking block (25) and the carrier strips (55, 57) of the bolt head carrier (13) is unimportant. It is only important that the foot strips (8) fit into the opening (53) formed in between the carrier strips (55, 57) in the bolt head carrier (13). Consequently, a simple and less precise manufacturing process is possible. Further, imprecise parts or replacement parts can be installed without further fitting.

The illustrated examples can be used, for instance, for small bore repeating weapons. The illustrated examples are particularly well suited for repeating shotguns such as pump-action shotguns. Further, the illustrated systems proves to be especially well-suited for repeating rifles which fire large cartridges, in particular for rifles that fire cartridges with a caliber of more than 15 mm. The two or more extractor hooks (61) reliably hold, convey and eject these very large cartridges.

The example repeating breech mechanisms disclosed herein may also be used for semi-automatic weapons by connecting a reloading mechanism (e.g., a gas regulator) with the handle or a pivot point provided in its place.

Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents. 

1. A firearm comprising: a barrel; a bolt head which is movable along a motion path; a locking block penetrating the bolt head and being movable in a direction substantially transverse to the motion path between a locked position and an unlocked position, the locking block locking the bolt head against movement along the motion path when the locking block is in the locked position; a bolt head carrier which is movable independently of the bolt head over a lost motion path and an initial path, and which is movable with the bolt head over an end path, the bolt head carrier including at least one surface positioned to force the locking block from the locked position to the unlocked position as the bolt head carrier travels the initial path, wherein, when moving rearward, the bolt head carrier travels the lost motion path before traveling the initial path, and the locking block remains in the locked position as the bolt head carrier travels the lost motion path; and a handle to move the bolt head carrier.
 2. A firearm as defined in claim 1, further comprising a housing defining a recess to receive the locking block when the locking block is in the locked position.
 3. A firearm as defined in claim 1, wherein a rear end of the barrel defines a recess to receive the locking block when the locking block is in the locked position.
 4. A firearm as defined in claim 1, further comprising a firing pin penetrating the bolt head.
 5. A firearm as defined in claim 4, wherein the locking block is penetrated by the firing pin, wherein the locking block permits free movement of the firing pin when the locking block is in the locked position, and blocks the firing pin in a withdrawn position when the locking block is in the unlocked position.
 6. A firearm as defined in claim 5, wherein the locking block comprises a beveled surface to force the firing pin into the withdrawn position as the locking block moves from the locked to the unlocked position.
 7. A firearm as defined in claim 1, wherein, when the locking block is in the locked position, the locking block engages in a recess in a component that is integrally formed with or secured to the barrel.
 8. A firearm as defined in claim 7, wherein the locking block includes a base having front and rear guide surfaces, the bolt head carrier includes front and rear driving plates which interact with the locking block such that: (a) when moving rearward over the initial path, the front driving plate of the bolt head carrier engages the front guide surface of the base of the locking block to thereby force the locking block from the locked position to the unlocked position, and (b) when moving rearward over the initial path, the rear driving plate of the bolt head carrier engages the rear guide surface of the base of the locking block to thereby force the locking block into the locked position, and wherein at least one of the front guide surface, the rear guide surface, the front driving plate, and the rear driving plate is beveled.
 9. A firearm as defined in claim 1, wherein the firearm is structured to fire shot cartridges or other cartridges with a caliber of more than 15 mm.
 10. A firearm comprising: a bolt head; a locking block penetrating the bolt head and being movable between a locked position and an unlocked position, the locking block locking the bolt head against movement when the locking block is in the locked position; a bolt head carrier which is movable over an initial path and an end path, the bolt head carrier carrying the bolt head when the bolt head carrier travels the end path, the bolt head carrier including at least one angular surface to move the locking block from the locked position to the unlocked position as the bolt head carrier travels the initial path, the bolt head carrier being movable over a lost-motion path during which the bolt head remains locked by the locking block; and an automatic charging mechanism to cycle the bolt head carrier when a shot is fired.
 11. A firearm as defined in claim 10, further comprising a housing defining a recess to receive the locking block when the locking block is in the locked position.
 12. A firearm as defined in claim 10, wherein a rear end of the barrel defines a recess to receive the locking block when the locking block is in the locked position.
 13. A firearm as defined in claim 10, further comprising a firing pin penetrating the bolt head.
 14. A firearm as defined in claim 13, wherein the locking block is penetrated by the firing pin, wherein the locking block permits free movement of the firing pin when the locking block is in the locked position, and blocks the firing pin in a withdrawn position when the locking block is in the unlocked position.
 15. A firearm as defined in claim 14, wherein the locking block comprises a beveled surface to force the firing pin into the withdrawn position as the locking block moves from the locked to the unlocked position.
 16. A firearm as defined in claim 10, wherein, when the locking block is in the locked position, the locking block engages in a recess in a component that is integrally formed with or secured to the barrel.
 17. A firearm as defined in claim 16, wherein the locking block includes a base having front and rear guide surfaces, the bolt head carrier includes front and rear driving plates which interact with the locking block such that: (a) when moving rearward over the initial path, the front driving plate of the bolt head carrier engages the front guide surface of the base of the locking block to thereby force the locking block from the locked position to the unlocked position, and (b) when moving rearward over the initial path, the rear driving plate of the bolt head carrier engages the rear guide surface of the base of the locking block to thereby force the locking block into the locked position, and wherein at least one of the front guide surface, the rear guide surface, the front driving plate, and the rear driving plate is beveled.
 18. A firearm as defined in claim 10, wherein the firearm is structured to fire shot cartridges or other cartridges with a caliber of more than 15 mm. 